Conical truss differential case



July 24, 1951 R BUCKNDALE I 2,561,335

CONICAL TRUSS DIFFERENTIAL CASE Filed March 13, 1946 3 Shets-Sheet 1 Fig "M W/ 47 28 59 52 a n 54 2 32 I, 30 4 I I 1 7 V 6 7 4 v w H I I], T r 36 54 63 3 46 I5 53 f 50 64 4/ INVENTOR.

Lawrence R. Buc/renda/e TEMrW A T TORNE KS July 24, 1951 1.. R. BUCKENDALE CONICAL TRUSS DIFFERENTIAL CASE 3 Sheets-Sheet 2 Filed March 15, 1946 July 24, 1951 R. BUCKENDALE CONICAL TRUSS DIFFERENTIAL CASE 5 Sheets-Sheet 5 Filed March 13, 1946 gym/Wm Patented July 24, 1951 CONICAL TRUSS DIFFERENTIAL CASE Lawrence R. Buckendale, Detroit, Mich., assignor to The Timken-Detroit Axle Company, Detroit, Mich., a corporation of Ohio Application March 13, 1946, Serial No. 653,980

16 Claims. (Cl. 74-713) This invention relates generally to differential drive axles and more particularly to an improved deflection resistant differential gear case construction.

In general the invention is concerned with makin the best possible structural use of the metal available for the differential gear case while at the same time staying within the space limitations of the differential carrier or other axle housing parts. In the construction hereinafter described I provide a differential case having greater strength than hitherto conventional differential cases of equivalent mass, and as a corollary I am enabled to obtain strength equivalent to such conventional cases using a smaller mass of metal. I have discovered that arrangement of the mass of the differential case to provide a maximum of metal as nearly as possible in the direct path of drive thrust forces so as to take as much load as possible in compression, and as much as possible of the remainder in bending, while holding tension stresses in the case to a minimum, provides a novel and useful structure which represents an important part of this invention.

I have discovered in the preferred embodiment of the invention that the hitherto conventional external reenforcing ribs of such cases can be omitted and their function increased and built into the case itself by constructing the case in generally conical mutually bracing sections secured rigidly together with their external surfaces lying in opposed conical envelopes externally unencumbered by reenforcing ribs or like projections so as to take full advantage of the permissible space within the axle housing part. The mass of metal of my novel case may thus be arranged and disposed as far radially outwardly as possible so as to provide a maximum amount of it in the direct line of pinion drive thrust.

It is therefore the major object of my invention to provide a novel differential gear case construction wherein the mass of metal is so distributed as to afford maximum strength for a given amount of metal.

A further object of this invention is to provide a differential case having a conical truss construction wherein external reenforcing ribs are omitted and the mass of metal is arranged to place as much of it as possible in the path of the drive thrust forces.

Other objects will become apparent as the description proceeds in connection with the accompanyin drawings, wherein:

Figure 1 is a top plan view, in horizontal section, of a differential illustrating one embodiment of my invention, the plane of the section being indicated by the section lines I--l of Figures 2 and 5;

Figure 2 is an end elevation of that section of the differential unit case shown to the left in Figure 1, and which carries the ring gear (omitted from Figure 2) Figure 3 is a section substantially along the line 3-.-3 of Figure 2;

Figure 4 is a section substantially alon the line 4-4 of Figure 2;

Figure 5 is an end elevation of that section of the differential unit case which mates with the section shown in Figure 2; and

Figure 6 is a side elevation of the case of Figure 5, partly in section as indicated by the line 66 of Figure 5.

Referring now in further detail to the drawing for the purpose of illustration, oppositely extending axle housing arms 2 and 4 are integrally joined by a central enlarged housin portion 6 which is open front and rear so as to provide the well known banjo type axle housing. The front opening 1 of the housing is surrounded by a reinforced carrier attachment flange 8 to which a differential carrier Ill is secured by studs I2 cooperating with a flange l4 integral with said carrier. The rear opening 15 of the central housing portion 6 is closed by a bowl or cover member It provided with a marginal flange ll Welded to the housing portion 6.

An integral pinion and shaft I8 is journalled at one end in a bearing cage assembly 20 which is piloted in an aperture 22 at the front of the carrier l0 and is secured thereto by any conventional means such as studs 23, along with a cover 24 which contains a dust seal unit 26. The pinion and shaft I8 is journalled at its rear end in a bearing 28 supported in a suitable integral boss 30 extending from the side of the carrier l0. Secured to the forward and external end 3| of said pinion and shaft I8 is any conventional means for securin said end to a driven propeller shaft (not shown).

The carrier H! has integrally formed at its sides a pair of aligned half cylindrical bosses 32 and 34, the rear halves of which are completed by identical half cylindrical caps 38 and 38 that are normally secured to the bosses 32 and 34 respectively by studs (not shown).

The differential unit includes a case for a spider, pinions and side gears comprising two opposed sections 40 and 4!, respectively. The mat- 3 ing faces of the opposed case sections, indicated at 52, are recessed to receive the cylindrical outer ends of the four arms of a spider 53 upon which diiierential pinions M are freely rotatably mounted. The two case sections are rigidly secured in compression by twelve or some suitable number of bolts 65 in a circle, to retain and support the difierential gearing in assembled relaticnship.

Case section 853 is of substantially greater outer diameter than any portion of the mating section 4|, and is formed with a peripheral flange 41 to the inner side face of which a beveled ring gear 43 is secured as by rivets d9 passing through openings Ed in the flange. Theflange ll is connected to a hub El by a relatively steep conical. wall 52 part of which lies directlyin the projected path of the drive thrust area between the ring gear 48 and pinion l8.

Case section 453 also has an integral inner side wall 53 extending inwardly from the flange and having a central opening in which the internally splined hub 54 of a .diilerential side gear 55-is journalled. The wall 53 has an outer conical portion and an inner substantially radial ,portion as best seen in Figure 4. Thehub of the case section iii is journalled in a suitable antifriction bearing '56 mounted inthe half boss and cap 36 and held againstvaxial movement by aretaining member 57 threaded into said boss and cap.

.A series of substantially equiangularly spaced internal radial ribs 58 are formed integral with wall 52, and they extend between the walls and .53 as best shown in Figures 1 and 3, thus greatly strengthening the case section ie? to resist the thrust of the pinion l8 against the ring ear 48.

"In order to provide for the insertion of the twelve bolts i5, and also to provide for access to their heads, the conical wall 52 has twelve cored holes 5.; therethrough, in axial alignment with the drilled holes 85 (Figure 3) whereby the-bolts tdpass through the inner side wall-53. ReferringtoFigures 2 and 4, the .inner side wall53 .is shown to be .provided with passages 6! therethrough, there being one such passage between each two adjacent ribs 58, to provide means for .fiuid lubricant to enter from the axle housing into .the chamber formed by the assembledcase sections it and 4|,and enclosing the pinion and side gears. Asbest shown in Figure 4, the oonical outer wall 520i case section M is thickened,

.as shown at 52, in those portions between the .coredholes 59 and where there are no ribs This further strengthens the conical wall 52.

Since case section lfilhasno externalribs Iain enabled to take full advantage 'of the available space within carrier liland so provide a rela tively steepcone at '52 thereby concentratinga large partof the metal of .case section Ail in the outer regions near the direct path oi drive thrust .from pinion I8 to. ring gear 48,.-and the arrange- .ment enables me to dispose theinnerribsbllfun "ther outwardly toward that path than would be possible in the prior art, to the same advantage. The steepness of cone .52 is preferablysuchthat v its extended envelope willencloseri e gear thus providing acompact thrust resistant as- .sembly.

The case section 4| is provided with anexternal conical wall.63..conne cting--a cylindrical'sectionfid with asmaller hub 65. The cylindrical section .fid-isthelargest part of-the case section 4!..and .has eight holes 56 therethrough. As

4 shown in Figure 5 the holes 66 are disposed in pairs, the pairs being grouped degrees apart. Between each pair of holes 66 is a hole 6'1, the holes 61 being 90 degrees apart. When the case sections 40 and 4| are assembled the holes 55 and 6? in case section 4| are in axial alignment with the twelve holes 60 in the case section 49.

The conical wall .63 is provided with four spaced apertures 68 to permit the entrance of lubricant into the assembled differential case, the apertures having the same angular disposition as the holes 6'1, as best shown in Figure 5. The conical wall 63 is depressed at each of the apertures as indicated at 69 to counteract the effect thata revolving conical surface would have in restricting the fiow of lubricant through apertures.63. At the apertures 68 the cylindrical section 64 has a radial wall as shown in Figure 6.

An inner wall 10 extends substantially radially inwardly and has a central bore providing a journal for thehubof theside gear 1:. The hub .65 of case section .4 is journalled in an .antifriction bearing '72 which is mounted intheihalf boss 34 and cap 38 and retained against axial movement by an annular member T3 which is threaded into the bossand cap. Internal rib members M between .the inner wall Hi, the conical wall 63 and the hub 65, strengthen the case sectiondl.

In order that the nuts on the bolts .46 will clear the exterior ofthe .com'cal wall 63, the case member M is provided with bosses 15 at each holeiifi, as best shown in Figures5 and 6. .Thusthe holes 66 are substantially longerthan the holes Gland the bolts llfipassing through these holes will also be longer, by an equal amount. In order that socket wrenches .m-aybe used on the nutsfor the bolts 46, the outersurface of the conical wallet may be slightly recessed adjacent reach-of the bosses 15 as indicated at Mon Figures 3 and 6.

Theaxle shafts 11 and 18 have externalsplines cooperating with internal splines on the side gears 55 and H which thereby rotate the shafts.

From the foregoing description it will be apparent that there has been provided a two-section "differential case wherein the rigidity for eachsection is obtained in large part from the coni al wall of each respectivesection. .A large part of the mass of metal of each case section is disposed as closely as possible in the path of the bolts 56 extend .through .a large portionof 'the'lengthof the assembled case sections 94B and M, a substantial portion .of the smaller .case sectionis under compression also, even when the assembled casing i under the thrust load fimposed by .the pinion l8.

My novel differential case thus comprises .a pair of opposed substantially conical sections which are secured together to provide an assembly which has maximum resistance to axial bending, thereby retaining the alignment of bearingsBB and 72 durin drive operation. The conical sections mutually brace each other, their internal-ribs aiding in resisting axial'bending of .theassembled case, and the novel structure providing optimum stress distribution.

In the assembly internal radial ribs 58 and M of the respective case sections are preferably longitudinally aligned for optimum mutual bending resistance, Ribs 58 and 14 effectively provide conical truss members within the case sections.

The invention may be embodied in other speciflc forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United states Letters Patent is:

1. In a two piece differential case for an automotive vehicle; a. first case section comp-rising a supporting hub, a spaced ring gear flange, a

conical wall connecting said hub and flange, an integral inner wall spaced from said conical wall and having a central opening, and integral web members joining said hub, flange, conical wall and inner wall: a second case section having a cylindrical portion, a supporting hub, a conical wall joining said cylindrical portion and hub, an inner wall integral with said conical wall, spaced from the hub thereof, and having a central opening; and bolts passing through the inner wall of said first case section and the cylindrical portion of said second case section to clamp the two sections together, said conical wall of the first case section being provided with openings in alignment with said bolts to provide access to said bolts and also being thickened in those portions between the openings and web members.

2. In a two piece differential case for an auto- ,motive vehicle; a first case section comprising a supporting hub, a spaced ring gear flange, a conical wall connecting said hub and flange, and an integral inner wall spaced from said conical wall and having a central opening; a second case section having a cylindrical portion having a mating engagement with the inner wall of the first case section, a supporting hub for said second case section and a conical wall joining said cylindrical portion and hub, a series of angularly spaced bosses projecting from said cylindrical portion and beyond said conical wall toprovide seats paralleling the plane of the joint between the first and second case sections; bolts passing through said cylindrical portion and bosses and the inner wall of said first case section, nuts on said bolts for clamping the case sections together, said seats providing proper engagement of the nuts or bolt heads with the outer surface of the second case sections, the conical wall of said second case section being provided with passages for lubricant and said cylindrical portion having a radial face at said passages, and clamping bolts passing through the cylindrical portion and the inner wall of said first case section at these points, the radial faces providing seats therefor.

3. A case section for a two piece differential case construction comprising a supporting hub, a spaced ring gear flange of substantially larger diameter than the hub, an integral conical wall connecting said hub and the outer periphery of said flange, and an integral inner wall connected to said flange in spaced relation to said conical wall, said inner wall having a substantially conical portion extending towards said hub and a 6 substantially radial portion at the end of said conical portion havin a central opening for journalling a side gear.

l. The case section described in claim 3 wherein a series of angularly spaced radial ribs are integral with and extend between said conical wall and said inner wall, and wherein said conical wall is thickened in those portions between the ribs.

5. A case section for a two piece differential case construction comprising a supporting hub, a spaced hollow cylindrical portion of substantially larger diameter spaced from and coaxial with said hub, a conical wall joining said cylindrical portion and hub, a series of angularly spaced bosses projecting from said cylindrical portion and beyond said conical wall to .provide radial seats, said bosses having central passageways for bolts or the like and means providing lubricant passages in said conical wall, said cylindrical portion having a radial face at said passages and also having openings for fastening elements normal to said radial face.

6. The device described in claim 5 wherein an inner wall having a central opening is provided integral with and extending substantially radially from said conical wall to support a side gear, and a series of angularly spaced ribs integral with and connecting said conical and inner walls.

7. In a differential case section, an external generally conical wall having no external reinforcing ribs, an integral internal wall axially spaced from said external wall having a conical portion extending in the direction of said external wall and having a terminal portion apertured to provide a journal for a differential side gear, a ring gear attachment flange surrounding and integrally joining the outer peripheries of said walls, said internal wall having a plurality of spaced bolt receiving openings for attachment of the case section to another differential case section, and longitudinally extending circumferentially spaced internal ribs within said case section integrally interconnecting said conical wall and said internal wall said conical wall being provided with apertures for access to bolts in said openings.

8. In a differential case section, an external wall surface lying in a substantially conical envelope and having no external reenforcing ribs, a hub integral with the smaller end of said wall, a ring gear secured to said case section adjacent the base of said external wall, said ring gear lying within the projected envelope of said external wall surface, an internal differential side gear supporting wall integral with said case section and extendin from said base toward said hub and terminating in a portion having a side gear receiving opening disposed axially outwardly of said ring gear, and integral longitudinally extending internal reenforcing ribs joining the interior of said external wall to said internal wall.

9. In a differential case assembly, two case sections each havin external walls with their outer surfaces lying in substantially conical envelopes and having no external reenforcing ribs, means securing said case sections together at their larger ends, intermediate internal walls in each of said sections centrally apertured to provide supports for the differential side gears, and circumferentially spaced longitudinal reenforcing webs in each of said case sections between the external and internal walls in each section.

.10. In the differential case assembly defined in claim 9, said webs in the respective case sections b'eing longitudinally alignedwhen the case sections are secured together.

1.1. In a diiferential assembly, two case sections each having their external W311 surfaces lying in substantially conical-envelopes with no ex- '-ternalreenforcing Webs, means for securing said case sections together-at their larger ends a ring gear'attac'hment flange integral with one of said case sections and encompassed by the projected envelope of the associated external wall surface of said one case section, and a plurality of circum'ferentia'lly spaced. axially extending integral reenforcing ribs-within each of said case sections to mntua lly brace the vassembly against bending.

12. In a differential assembly, a first case sec- =tion having at opposite ends a supporting 'hub and a larger attachment rim, an integral wall jcin'ing'said hiib and rim and having its external surface free of reenforcing ribs and lying'in a --szibstantia1ly conical envelope flaring from said hu'b,a ring gear attachment flange of larger diameter than said Tim integral with said wall and a ring gear thereon bo'tlrlying substantially within the extended envelope of said surface, a

'p"-l-urality :of axially extending internal ne'enforcing ribs within said ease section integral with said We'll, sa'id'wall'being of relativei-y'steep slope with 'respect to "the'hub for disposing an appreciable amount'o'f metal of said casing section outwardly at the periphery "of "said case section so --as to provide optimum'direct backing for the rin gear against thrust'forces that arise when the ring gear is driven'by the usual drive pinion, 'a-"seeond case section having a-rim secured to the rmmr said first case section and "a smaller axially spaced hub, an external wall integrally joining the hub and rim'of said second case section and "having its external surface free of reen'forcing ribs and lying'in asubs'tantially conical envelope, and a plurality of -'axi'ally extending internal reenforcing ribs integral with said sec- "ond casing section wall.

13. 1n the differential assembly defined in claimlfiya radially extending internal Wall within each of said case sections intermediate the and rim and apertured'for journalling side gears of the differential, and said reen'forcing ribs in each-case section extending between the external and internal walls.

14. In a differential assembly, a'casing section having -an outer conical Wall free of external re- "enforcing ribs, the "outer periphery of said wall providing 'a ring gear attachment flange, a 'hub integral with the other'end-of said-wall, an in- *tegral internalwall inwardly of said fian'ge "hav- "ing'in succession a radial'bolting face, 'anfinclined portion sloping toward the hub and a centrally apertured radial portion, and integral reenforcing ribs'connecting the hub and both walls.

15. 'In 'a differential case assembly, two case sections "each having hubs and larger mated attachment faces at opposite ends and integral "external substantially conical wallls constructed'and "arranged for disposing the mass or said case sections mainly at the periphery of said'assembly, means for securingsaid casesections together at said mated attachment'faces, a ring-gear secured about-and upon one -of said case sections radially outwardly of said attachment faces 'but lying within the projected envelope of the external "conical wall of said one case sections, and a: series of circumferentially spaced longitudinally extending reen'forcing ribs within each case section "for mutually bracing the-assembly against axial bending.

16. A case-section for a two piece difierential case construction comprising a supporting hub, a spaced :ring gear 'fiangefo'f substantially larger diameter than the 'hubyan integral c'onical'wall connecting said hub and the :outer periphery of said flange, an integral inner wallzconnected to i said flangeinspaced :reiation to said 'conical wall, said inner wall having r a substantially conical portion extending :toward said :hub sand pa substantially. radial portion at thes'end of said iconical portion having 'a "central iopening "for journailing a side gear, and a plurality -of "spaced radial ribs internally joining said conical wall with said hub, flangeand inner wall radiallyoutwardly of said opening.

LAWRENCER. BU

REFERENCES CITED The following references are of record in the i'file of this patent:

UNITED .STATES .PATENTS 'Number Name .Date

1,226,742 Baker May 22,191? 1,987,716 Skelton Jan. 15, 1935 2,056,881 Alden .Oct.'6, 1936 2,133,112 Ormsby Oct. 11, 1938 2,183,667 Buckendale Dec. :19, 1939 2,219,025 Vandenberg Oct.. 22, 1940 

